Variabilidade genética e ecológica de Stylosanthes macrocephala determinadas por RAPD e SIG

Abstract

Resumo -Stylosanthes macrocephala M. B. Ferr. et S. Costa é uma leguminosa utilizada sob consorciação em pastagens, adubação e recuperação de áreas degradadas. A falta de características morfológicas e agronômicas estáveis e de informações ecogeográficas dos locais de coleta dos acessos tem dificultado o melhoramento genético da espécie. A fim de obter descritores ecológicos, moleculares e avaliar a variabilidade genética da coleção de S. macrocephala, 87 acessos foram analisados com o auxílio do Sistema de Informações Geográficas (SIG) e de marcadores moleculares RAPD. Os acessos provieram de sete Estados, cinco bacias hidrográficas, sete tipos de vegetação e sete tipos de solos. As altitudes dos locais de coleta variaram de 1 a 1.298 m e a pluviometria anual média de 550 a 2.870 mm. A variabilidade de descritores ecológicos sugeriu diversidade adaptativa na coleção. Com base em 161 marcadores RAPD, verificou-se que as distâncias genéticas entre os acessos de S. macrocephala variaram entre 0,02 e 0,42. Com base nessas distâncias, dez grupos de similaridade genética foram estabelecidos. Observou-se tendência de separação por bacias hidrográficas e elevada variabilidade genética entre os acessos coletados nos estados da Bahia e de Minas Gerais. A alta variabilidade genética da coleção de S. macrocephala evidencia a importância desses acessos para futuros trabalhos de melhoramento genético.Termos para indexação: diversidade genética, marcadores moleculares, germoplasma, leguminosa forrageira, Sistema de Informação Geográfica. Genetic and ecological variability of Stylosanthes macrocephala determined by RAPD markers and GISAbstract -Stylosanthes macrocephala M. B. Ferr et S. Costa is a leguminous species used as forage, cover crop and as a pioneer plant to recover degraded areas. Inexistence of stable morphological descriptors and lack of ecogeographic information about collecting sites bring difficulties to the studies of this species. The objective of this work was to use the geographic information system (GIS) and RAPD markers to obtain ecological and molecular descriptors and to study the genetic variability of 87 S. macrocephala accessions. The accessions were collected from different ecogeographical areas in seven Brazilian States, five hydrographic regions, seven vegetation types and seven soil types. Collecting sites ranged from 1 to 1,298 m above sea level with annual rainfall from 550 to 2,870 mm. Accession distribution along those diverse ecosystems indicate high adaptive diversity. Using 161 RAPD markers, genetic distances between accessions ranged from 0.02 to 0.42. These genetic distances allowed the establishment of ten genetic groups. Accessions collected in specific hydrographic region tended to be grouped in the same genetic group. Accessions collected in Bahia and Minas Gerais States showed high genetic variability. The high genetic variability observed in the accessions showed the importance of this S. macrocephala collection for breeding programs.

GENETIC DIVERSITY IN ACCESSIONS OF Stylosanthes spp. USING MORPHOAGRONOMIC DESCRIPTORS

“…However, studies with Stylosanthes in other regions of the country showed that the genetic variability between and within species of Stylosanthes is related to different regions of collection (BARROS et al, 2005;SANTANA et al, 2012), which was not observed in the present study. In other species of the genus Stylosanthes (S. capitata and S. guianenses), the presence of pollinating insects increased the crossing rates by 31% and 26%, respectively, as well as changed the fertilization rate in the progeny (SANTOS-GARCIA et al, 2011;, favouring the genetic variation in this material.…”

Evaluation of genetic similarity between accessions of Pityrocarpa moniliformis (angico-de-bezerro) using RAPD markers

“…Group I included the accessions BGFAB1, BGFAB2, BG-FAB4, BGFAB6, BGFAB9, and BGFAB7, collected in São João, PI, and accession BGFAB8, collected in Teresina, PI, suggesting that the last did not originate from the area in which it was collected. Groups II, III and IV comprised one accession each (BGFAB5, BGFAB10 and BGFAB3, respectively), indicating that the diversity of the species could be better exploited if more accessions were collected, confirming the conclusion of Barros et al (2005) based on the identification of groups of S. macrocephala containing few accessions. When individual accessions were pairwise compared, the highest genetic similarity coefficients were observed between group I accessions BGFAB7 from Teresina and BGFAB8 from São João and accessions BGFAB6 and BGFAB9 from São João, while the lowest coefficient was observed between accessions BGFAB10 (group III) and BGFAB3 (group IV).…”

“…The coefficients of genetic similarity between accessions of P. moniliformis ranged from 0.11 to 0.56 (Table 2). This variation was greater than that observed with domesticated and autogamous forage legumes such as Stylosanthes macrocephala (Barros et al, 2005) and Vigna radiata (Lakhanpaul et al, 2000). Table 2.…”

Genetic diversity of gabiroba based on random amplified polymorphic DNA markers and morphological characteristics

“…DNA was amplified according to Barros et al (2005). To obtain the RAPD markers, 12 Operon ® primers were used: OPA (01, 04, 08, 09, 18, and 20), OPM (03), OPS (07), OPV (05 and 12), OPAB (09), and OPAF (05).…”